jReject is a lightweight (7.05 KB excluding images and CSS) jQuery plugin that can be used to prompt users to upgrade their browser in a modal popup based on browser, bowser version, platform or rendering engine – all of which can be customised.

If the users browser does not meet your requirements a customisable message can be displayed to prompt the user to upgrade from a selection (also customisable) of the latest browsers.

The user is also given the option to carry on browsing the site if they acknowledge a reduced experience. If a user chooses to continue viewing the site, the prompt is prevented from being displayed again within the session.